1. Field of the Invention
The present invention relates generally to an Internet Protocol (IP)-based mobile communication system supporting a multimedia service, and more particularly to a method and system for processing a control message.
2. Description of the Related Art
IP-based systems are provided with multiple servers for processing service requests by distributing multiple users whose service requests are concentrated on a specific IP address.
As the number of subscribed users increases, the number of messages to be simultaneously processed increases. In this case, an IP Multimedia Subsystem (IMS) should increase the call processing capacity of an application server for an application program mapped to an associated service on the basis of IP network system characteristics or should distribute the users using multiple application servers.
Among methods for distributing the users, the most direct method is to distribute load across an arbitrary application server by installing multiple application servers with the same function and dividing and registering information of multiple subscribers in a predefined home subscriber server.
However, a method for statically pre-allocating an application server on the basis of subscriber information is disadvantageous in that operation and maintenance costs increase since the subscriber information should be periodically updated under variable operating environments. Moreover, there is a problem in that a user can never use any service when the operation of a specific application server allocated to the user is stopped.
A method for dynamically allocating a user to an application server involves configuring a logical application server into which multiple application servers are integrated through a distributor. At least one distributor distributes load by selecting one application server from among the multiple application servers and processing and sending a request message received from a user. At this time, since distributors share user allocation information for the application servers, the user request may be constantly processed in the same application server even though the user request passes through any distributor. Since the request message should pass through a distributor in the dynamic allocation method, re-transmission may lead to delay. When a non-standard control protocol is used between application servers for the load distribution, it may not be applied between heterogeneous application servers.
There is currently a need for a method for distributing load by dynamically allocating an application server in an existing IMS system.